Earth boring bit thrust bearing

ABSTRACT

Intermediate thrust elements are positioned between the cutters and the bearing pins of an earth boring bit. Each intermediate thrust element is located between a thrust surface on a bearing pin and a thrust surface on the associated cutter. The intermediate thrust elements aid stabilization of the rotating cutter, promote cutter rotation and extend the lifetime of the bit.

1 1March 13, 1973 United States Patent 1 1 McCallum ....308/8.2....308/8.2 Schlumpfet .....308/8 2 54] EARTH BORING BIT THRUST3,656,764 4 1972 Robinson.........................

BEARING 2,444,724 7 1943 Brown 2,065,742 12/1936 Reed [75] Inventor:Hugh F. McCallum, H1bb1ng, Mmn. 2,075,999 4/1937 Reed [73] Assigneez2,104,819 1/1938 [22] Filed:

Dresser Industries, Inc., Dallas, Tex.

May 21, 1971 Primary Examiner-David H. Brown Attorney-Robert W. Mayer,Thomas P. Hubbard, Jr., Daniel Rubin, Raymond T. Majesko, Roy L. VanWinkle, William E. Johnson, Jr. and Eddie E. Scott [211 App]. No.:145,651

T C A R T S B A n 5 2 0 H 89 0-D 31 92 2E 7" 3 u 5 7 1 u QML Um NH 55 [l[58] Field of Search 372; 308/82 Intermediate thrust elements arepositioned between the cutters and the bearing pins of an earth boringbit. References Cited Each intermediate thrust element is locatedbetween 21 UNITED STATES PATENTS thrust surface on a bearing pin and athrust surface on the associated cutter. The intermediate thrust ele- 6t 0 m m 1. ub 6 e a 5 uf co m 2.6 mm .E

41 F a MK n l .1 e W mr t r. elm D 0 6 m s, e m 8 0 a Zn 1 m 0 b 9 mmXXX. 222 777W 333 ///3 555 777 4 mfl dn 3 RFH 609 356 999 111 Ill 07 l 144 6 2345 6 6 3 4 0030 s ooo 0 5 4 6 2233 PATENTEBHAR 1 3197s SHEET 1 or2 FIG. I

PRIOR ART FIG. 3

INVENTOR HUGH F. McCALLUM ATTORNEY Pmmmmm 3,720,274

sum 2 or 2 FIG. 4

FIG. 5

HO I06 FIG. 6

, INVENTOR HUGH F. MCCALLUM EARTH BORING BIT TIIRUST BEARING BACKGROUNDOF THE INVENTION The present invention relates to the art of earthboring and more particularly to a rolling cone rock bit. The presentinvention is especially adapted for use on that type of rock bitpopularly known as a three-cone bit; however, its use is not restrictedthereto and the present invention can be used in other types of rotaryrock bits.

A three-cone rotary rock bit is adapted to be connected as a lowermember of a rotary drill string. As the drill string is rotated, the bitdisintegrates the formations to form an earth borehole. The three-conerotary rock bit includes three individual arms that extend angularlydownward from the main body of the bit. The lower end of each arm isshapedto form a spindle or hearing pin. A cone cutter is mounted uponeach bearing pin and adapted to rotate thereon. Individual bearingsystems promote rotation of the cone cutter. These bearing systems havetraditionally been roller bearings, ball bearings, friction bearings ora combination of the aforementioned bearings. The cone cutters includecutting structure on their outer surfaces that serve to disintegrate theformation as the bit is rotated.

In addition tothe rotationalforces, the bit is subjected to a thrustload during operation. The weight of the drill string and the downwardforce applied by the rotary drill equipment apply a substantial thrustload upon the earth boring bit. In prior art earth boring bits, thisthrust load was taken by a thrust button in the nose of the cone cutterwhich rotated against a hard faced surface on the inner end of thebearing pin and by the ball bearing system of the earth boring bit.

Prior art earth boring bits have experienced early failure because oftheir inability to support the extensive thrust loading. The thrustbutton and ball bearing systems have been unable to adequately supportthe thrust loads under certain drilling conditions and excessive wear ofthe elements subjected to the thrust forces has resulted in the conecutters becoming disoriented with respect to the bearing pins with aconsequent early failure of the bit. Certain earth boring bits used inthe mining industry and popularly called blast or shothole bits havebeen constructed with an outer roller bearing system and an inner ballbearing system. The usual inner bearing system, generally a rollerbearing or friction hearing, has been omitted. The space left by theomission of the inner bearing system has created a problem in that onoccasion the cone cutter becomes disoriented with respect to the bearingpin resulting in early failure of the bit.

DESCRIPTION OF THE PRIOR ART ball-friction bearing system. The innermostpart of the bearing cavity formed in the cutter includes a thrust buttonwhich bears against the lowermost end of the bearing pin to absorbthrust forces. The ball bearing system of this bit also aids inabsorbing the thrust forces. Another earth boring bit shown in thispatent discloses an earth boring bit with a friction, ball-frictionbearing system.

SUMMARY OF THE INVENTION The present invention provides an improvedbearing system for a rolling cone earth boring bit that will supportthrust loads and prevent the cone cutters from becoming disoriented onthe bearing pins. The present invention stabilizes the cone cutters,increases bearing life, reduces heat generation, provides anintermediate thrust element between the bearing pin and the interior ofthe cutter shell thereby providing a material that may be morecompatible with the metals that are used for the bearing pin and thecutter shell and in general provides an improved earth boring bit. Theintermediate thrust element is located between a thrust surface on thebearing pin and a thrust surface on the associated cone cutter. Theintermediate thrust element is generally not affixed to the bearing pinor the cutter shellbut is allowed to float freely between the bearingpin and the cutter shell.

It is therefore an object of the present invention to provide animproved rolling coneearth boring bit.

It is a further object ofthe present invention to provide a rolling coneearth boring bit that will support thrust loads better than bits of theprior art.

It is a still further object of the present invention to provide betterstabilization of the cutters of an earth boring bit.

It is a still further object of the present invention to provide anintermediate element between the bearing pins and the cutters of anearth boring bit.

The above and other objects and advantages of the present invention willbecome apparent from a consideration of the following detaileddescription of the invention when taken in conjunction with the drawing.

BRIEF DESCRIPTION OF TI-IE DRAWING FIG. 1 illustrates an earth boringbit of the prior art.

FIG. 2 is a sectional view of one arm of an earth boring bit of thepresent invention.

FIG. 3 is an enlarged view of a portion of the bit shown in FIG. 2.

FIG. 4 illustrates one embodiment of intermediate thrust element of thepresent invention.

H6. 5 illustrates diagrammatically some of the forces imposed upon theelements of an earth boring bit during drilling.

FIG. 6 illustrates another embodiment of an intermediate thrust elementof the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1 an earthboring bit of the prior art is shown and designated generally by thereference number 10. The bit 10 includes a body portion 12 having anupper portion 14 that is threaded to allow bit to be connected to arotary drill string (not shown). A multiplicity of arms 16, 16, etc.,extend from body portion 12. The lower portion of each arm 16, 16',etc., forms a bearing pin 18 that projects into a recess 20 formed inthe associated rotary cutter 22. The cutter 22 is journaled on bearingpin 18 by roller bearings 24, ball bearings 26 and thrust button 28. Apassage system 30 provides conduits to transport cooling fluid to thebearings.

The prior art earth boring bit 10 supports the entire thrust load withthe ball bearings 26 and the thrust button 28. As the ball race 32wears, the bit 10 tends to become unstable and an increased load isplaced upon the roller bearings 26. The cone cutter 22 tends to becomecocked with respect to the bearing pin 18 since cutter 22 wants to pivotabout thrust button 28. The bit 10 consequently experiences earlyfailure.

In addition, certain of the prior art bits are constructed without theusual inner bearing system. For example, the inner friction bearingsystem may be deleted in the roller-ball-friction type bits. The spaceleft by the deletion of this bearing system aggravates the stabilizationproblem previously discussed. The space 34 in the prior art bit 10 is anexample of this type of construction.

A single arm 36 of an earth boring bit constructed in accordance withthe teachings of the present invention is shown in FIG. 2. The lowerportion of arm 36 forms a bearing pin 38. The bearing pin 38 projectsinto a recess 40 formed in cutter 42. The cutter 42 is journaled onhearing pin 38 by roller bearing 44, ball bearings 46 and thrust button48. A passage system 50 provides conduits to transport cooling fluid tothe bearings. The cutter 42 includes a number of inserts 52 projectingfrom its outer surface that serve to disintegrate the formations duringdrilling. An intermediate element 54 is positioned in recess 50 betweena thrust surface 56 on bearing pin 38 and a thrust surface 58 on cutter42. The thrust element 54 is not affixed to the bearing pin 38 or thecutter 42 but is allowed to float freely around bearing pin 38.

Referring now to FIG. 3 an enlarged view of the intermediate element 54,bearing pin 38 and cutter 42 taken from area 3 of FIG. 2 is shown. Theintermediate element 54 forms an annular ring that completely encirclesthe bearing pin 38. The central opening 60 of intermediate element 54 isof sufficient size that it does not restrict the cooling fluid emergingfrom passage system 50. A thrust surface 62 on intermediate element 54bears against thrust surface 56 on bearing pin 38 and a thrust surface64 bears against thrust surface 58 on cutter 42. The intermediateelement 54 is free to rotate with cutter 42, remain relativelystationary with hearing pin 38 or rotate independently.

A top view of intermediate element 54 is shown in FIG, 4. Theintermediate element 54 is constructed from a material that iscompatible with the bearing pin material and the cutter material. Inthis embodiment, the intermediate element 54 is constructed of A.S.T.M.;B148, alloy 9C. The intermediate element 54 improves the performance ofthe bit and increases its lifetime. The intermediate element 54 helpssupport the thrust load, aids stabilizing of the bit, reduces heatgeneration thereby allowing the hearings to run cooler and provides amaterial that may be more compatible with the bearing pin and cuttermaterials.

In addition to the rotary forces applied to a bit during drilling, asubstantial thrust load is imposed upon the bit. The bit must supportboth the weight of the drill string and the load applied to the drillstring by the rotary equipment. The more important components of thethrust load and their effect on the bit are illustrated in FIG. 5. Thethrust load consists of a horizontal component 66 and a verticalcomponent 68. This load 66 and 68 must be transmitted from the cutter 72to the bearing pin 74. Earth boring bits of the prior art would supportthe thrust load almost entirely by the thrust button 76 and the ballbearing system 78. THus the components 66 and 68 would be transmitted tobit as components 80, 82, 84 and 86. However, as the drilling operationproceeded, the bearing system 78 would tend to wear and enlarge ballrace 88. As this happened, the cutter 72 would become disoriented onhearing pin 74 and an increasingly larger load component placed upon theroller bearing system 92. The increased load 90 would produce an earlyfailure of the roller bearing system 92 and a consequent early failureof the bit.

The provision of an intermediate element 94 between a thrust surface 96on hearing pin 74 and a thrust surface 98 on cutter 72 helps support thethrust load, stabilizes cutter 72 and promotes rotation of cutter 72.Intermediate element 94 receives a portion of the thrust load asillustrated by components 100 and 102. This helps prevent cutter 72 frombecoming disoriented upon bearing pin 74 thereby reducing the loadcomponent 90 acting against the roller bearing system 92. Theintermediate element 94 may be left to float freely between cutter 72and bearing pin 74 with the relative rotational speeds betweenintermediate element 94 and the surfaces 96 and 98 being less than ifsurfaces 96 and 98 were running directly against each other. Inaddition, intermediate element 94 may be constructed of a material thathas greater friction bearing compatibility with the bearing pin materialand the cutter material than they would have with each other.

In the embodiment of the invention shown in FIGS. 3', 4 and 5, theintermediate element 54 is constructed of materials that provide thesurfaces 62 and 64 with anti-galling properties. The entire intermediateelement may be constructed of the material having antigalling propertiesor only the outer portion of the intermediate element may include thematerials having these properties. The anti-galling materials may coverthe entire surface or the anti-galling materials may be interspersedwith other materials. In other embodiments of the invention, theintermediate element may be constructed of materials that provide itsouter surfaces with hard wear resistant properties. For example, theintermediate element 94 shown in FIG. 5 may be constructed of A.I.S.I.440C Stainless Steel. The hard wear resistant materials may cover theentire surface or the wear resistant materials may be interspersed withother materials. In the preferred embodiment of the invention theintermediate element has been shown as an annular ring; however, othershapes and forms of the intermediate element are contemplated. Theintermediate element 104 shown in FIG. 5 consists of two semi-circularsections 106 and 108. The surfaces 110 and 112 of sections 106 and 108must be compatible with the materials of the bearing pin and cutter thatthey run against. Sections 106 and 108 may be constructed of a hard wearresistant material selected from the group consisting of hardened steel,hardened aluminum bronze and tungsten carbide. Alternatively, sections106 and 108 may be constructed of an anti-galling material selected fromthe group consisting of copperbased alloys, silver babbitt metal,aluminum and zinc. Instead of the entire intermediate element beingconstructed of one of the materials mentioned above, the

intermediate element may be a mixture of the materials; a material maybe plated on the outer surface of the intermediate element or thesurface may be given the above-mentioned properties by other process.For example, the intermediate element may have surface grooves filledwith an anti-galling material or the intermediate element may be alaminated polytetrafluoroethylene fiber washer.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. An earth boring bit, comprising:

a bit body having an upper end eonnectable with a rotary drill string;at least one bearing pin extending from said bit body, said bearing pinhaving a first portion with a first diameter, a second portion with asecond diame ter, said second diameter being smaller than said firstdiameter, and a bearing pin thrust surface between said first portionand said second portion;

a cutter member rotatably positioned on said bearing pin, said cuttermember having a first inner portion with a diameter larger than saidbearing pin first diameter and a second inner portion with a diametersmaller than said bearing pin first diameter but larger than saidbearing pin second diameter, with a cutter member thrust surface on theinner portion of said cutter member between said first inner portion andsaid second inner portion;

bearing means between said bearing pin and said cutter member forpromoting rotation of said cutter member; and

an intermediate element positioned between said bearing pin thrustsurface and said cutter member thrust surface, said intermediate elementhaving a first thrust surface opposite said bearing pin thrust surfaceand a second thrust surface opposite said cutter member thrust surface.

2. The earth boring bit of claim 1 wherein the first and second thrustsurfaces of said intermediate element have wear resistantcharacteristics.

3. The earth boring bit of claim 1 wherein the first and second thrustsurfaces of said intermediate element have anti-galling characteristics.

4. The earth boring bit of claim 1 wherein the first and second thrustsurfaces of said intermediate element have areas with wear resistantcharacteristics and areas with anti-galling characteristics.

5. The earth boring bit of claim 1 wherein said intermediate element isconstructed from a material having anti-galling characteristics.

6. The earth boring bit of claim 1 wherein said inter mediate elementincludes materials with wear resistant characteristics and materialswith anti-galling characteristics.

7. The earth boring bit of claim 1 wherein the inter mediate thrustelement is constructed from a material selected from the groupconsisting of hardened steel, hardened aluminum bronze and tungstencarbide.

8. The earth boring bit of claim 1 wherein the intermediate thrustelement is constructed from a material selected from the groupconsisting of carburized stainless steel, hardened alloy steel andhardened tool steel.

9. The earth boring bit of claim 1 wherein the intermediate thrustelement is' constructed from a material selected from the groupconsisting of copper-based alloys, silver, babbitt metal, aluminum andzinc.

* II i i

1. An earth boring bit, comprising: a bit body having an upper endconnectable with a rotary drill string; at least one bearing pinextending from said bit body, said bearing pin having a first portionwith a first diameter, a second portion with a second diameter, saidsecond diameter being smaller than said first diameter, and a bearingpin thrust surface between said first portion and said second portion; aCutter member rotatably positioned on said bearing pin, said cuttermember having a first inner portion with a diameter larger than saidbearing pin first diameter and a second inner portion with a diametersmaller than said bearing pin first diameter but larger than saidbearing pin second diameter, with a cutter member thrust surface on theinner portion of said cutter member between said first inner portion andsaid second inner portion; bearing means between said bearing pin andsaid cutter member for promoting rotation of said cutter member; and anintermediate element positioned between said bearing pin thrust surfaceand said cutter member thrust surface, said intermediate element havinga first thrust surface opposite said bearing pin thrust surface and asecond thrust surface opposite said cutter member thrust surface.
 1. Anearth boring bit, comprising: a bit body having an upper end connectablewith a rotary drill string; at least one bearing pin extending from saidbit body, said bearing pin having a first portion with a first diameter,a second portion with a second diameter, said second diameter beingsmaller than said first diameter, and a bearing pin thrust surfacebetween said first portion and said second portion; a Cutter memberrotatably positioned on said bearing pin, said cutter member having afirst inner portion with a diameter larger than said bearing pin firstdiameter and a second inner portion with a diameter smaller than saidbearing pin first diameter but larger than said bearing pin seconddiameter, with a cutter member thrust surface on the inner portion ofsaid cutter member between said first inner portion and said secondinner portion; bearing means between said bearing pin and said cuttermember for promoting rotation of said cutter member; and an intermediateelement positioned between said bearing pin thrust surface and saidcutter member thrust surface, said intermediate element having a firstthrust surface opposite said bearing pin thrust surface and a secondthrust surface opposite said cutter member thrust surface.
 2. The earthboring bit of claim 1 wherein the first and second thrust surfaces ofsaid intermediate element have wear resistant characteristics.
 3. Theearth boring bit of claim 1 wherein the first and second thrust surfacesof said intermediate element have anti-galling characteristics.
 4. Theearth boring bit of claim 1 wherein the first and second thrust surfacesof said intermediate element have areas with wear resistantcharacteristics and areas with anti-galling characteristics.
 5. Theearth boring bit of claim 1 wherein said intermediate element isconstructed from a material having anti-galling characteristics.
 6. Theearth boring bit of claim 1 wherein said intermediate element includesmaterials with wear resistant characteristics and materials withanti-galling characteristics.
 7. The earth boring bit of claim 1 whereinthe intermediate thrust element is constructed from a material selectedfrom the group consisting of hardened steel, hardened aluminum bronzeand tungsten carbide.
 8. The earth boring bit of claim 1 wherein theintermediate thrust element is constructed from a material selected fromthe group consisting of carburized stainless steel, hardened alloy steeland hardened tool steel.